F-22 production ends at 187, F-35 production accelerated

[Spring]

There are different kind of radars, which work on different principies

There is not such thing as "magic stealth", in which you will be detected when is too late...no, not in the real world

The B-2 was designed as a penetrator with stealth on mind...later they fit a terrain following radar on it....try to guess why

About the F-22 and the program itself, well, after 8 years of corporative advertising somewhat supported by a friendly administration, we are looking the facts, i will not say the F-22 was a failure, but it was not a success, not because polititians, but because the program

Ok, lets check the facts

1-ATF program, design chosen and tested very different with the original model wanted by the USAF

2-ATF testing, a joke itself, no 9gs achieved, no supercruiser (max. M1.2 supercruiser, with max AB velocity of M1.6), no inflight RCS testing

3-F-22 chosen, some requirements lowered to met the especifications of the program, the raptor get 5-6 tons of overweight due structural issues, supercruiser failed, just the mythic stealth keept, and nobody knows if the requirement was meet

4-F-22 on service, a nightmare for maintenance, a lot of issues, blaming again..the mythic stealthy proprties, which again, can't be confirmed..while on excersices the raptor has performed somewhat good with readiness numbers, but for overall it readiness is only 60%..stealth maintenace?, i don't think so..

After all these problems, i'm not that surprised the USAF is not asking for more

 

[donnage99]

There are different kind of radars, which work on different principies
There is not such thing as "magic stealth", in which you will be detected when is too late...no, not in the real world

Err, thank you for stating the obvious that nobody even argued against to begin with! Moving on!

 

[Spring]

I'm not talking about radars by frequency class, to be exactly

You don't need low frequency to detect one stealthy aircraft at 200km

I think it's reasonable to assume the Russians would like to test their radars on the F-22 as much as possible. And as they get to do that, they might know little by little what works better against it

I'm more than sure the russians at least have a estimative of the F-22 radar signature, with all these patrols of Bears..but they will want to "study" it for it IFF system and anyway any RCS vaue is important from a mig-21 to a C-5, not because they are afraid of if LO...after all they got a fine example in 1999

Same as the F-16 signature , the F-15 one etc..

that doesn't get around the low observable shaping,

The return is relative with the angle of incidence, phasing the wave components can affect the angle of return regarding or not the shape of the exposed surface, not saying is completelly doable on complex shapes, but on general you will get the desired result

One last thing, remember the modern "LO" concepts are based on shape and forms , while the absorsion is secundary, meaning that , for energy conservation, the RCS of a stealthy airplane will be even higher than one convencional plane at certain angles

 

[Spring]

Oh, BTW, what kind of shapping has the F-22 to become very stealthy?

I can confirm somewhat , the F-117 overall shape, whit almost all it surface avoiding either the ground, or the front, it was designed for that, even the tail was designed in that way, until they found aerodynamic issues.

The leading edge of the Nighthawk angled at 70º, for a subsonic aircraft, obviously a major stealthy feature

Don't get me wrong, i have studied a bit the F-22, i have followed it progress, but a bit "disconnected" with all the advertising, without all the aircraft promotion, i really don't think it design is that stealthy, but then is a compromise with other features, it has measures to reduce it RCS, but hardly, very hardly i will believe it RCS is near as is claimed on the media, or is nearly stealthy as the F-117

 

[overscan (PaulMM)]

Almost everything is aligned on the F-22. See this crude overlay I knocked up in 5 minutes.

 

[Spring]

If i get a plane with many 90º aligned angles , then the plane should be stealthier?

I dont think so, but then why it has these aligned angles? to control better the RCS measuring, i mean, the alignement does not reduce the base RCS, but help to know better -with the related software- which RCS is returning, and at which orientation

The F-23 dont have many aligned shapes, not as many as the F-22, but has less congruent angles (for it profile) and a sharper nose, with most of it area facing upwards

Then again , the F-22 has measures to reduce and control it RCS, but then that does not mean it RCS is lower than other stealthier aircraft

 

[overscan (PaulMM)]

No, you are completely missing the point of planform alignment. The point is to minimise the number of possible angles that large amounts of radar energy is dumped in. By aligning all the doors and other edges with the leading edge angle, there are a few angles where you get a semi-decent return instead of many possible angles where radar energy reflects off various parts - a door edge, a fin, a pylon, whatever. The designer of the stealth aircraft then tries to make sure those very small number of visible angles are pointing in non-useful directions. So, when you are travelling along in your Su-35 with its big radar, and happen to send a radar signal out that hits the F-22 at 90 degrees to its wing leading edge, and you get a brief moment where you see something on the screen. Then, your relative positions change, the angles no longer make 90 degrees and the radar energy bounces off harmlessly in another direction. Your blip vanishes.

Yes, the YF-23 took this even further by having even less "spikes" on its RCS.

 

[Spring]

What does really matter for a real RCS decrease is the angle and the orientation of the shape/face, not how many aligned surfaces you get

Again

If i get a plane with many 90º aligned angles , then the plane should be stealthier?

You dont see it on a relative way, you can get many alignements like the f-22, or just a smooth angled line, for the F23...

 

[mz]

Spring, this is in good tone, you really should read some basics on stealth.

It's just like Overscan said.
Exactly because of energy conservation, it's wiser to radiate all the incoming radar energy back in only certain angles, than in all angles. Sure, the radar return in those very narrow angles is huge, but there are operational reasons why it's better that way: the sky is big and there is not likely anyone just exactly there.

Also, this is a slightly different issue: you want to avoid corner reflectors that reflect directly back to the sender (two bounces). For example an old fashioned sharp non-blended wing-body intersection would form a 90 degree corner reflector when viewed by a radar from lower down on the side. Sort of an "armpit".

 

[LowObservable]

It seems to be from time to time a job I have on this forum is to point out to prolific posters of craziness like Voidmage the wrongness of what they write.

I know that feeling all too well. ;D

To underline what Overscan and Mz said: The first thing you do in LO shaping is to encourage the energy to scatter away from the radar.

Where this is no longer possible (as on the edges) you manage the signature rather than reducing it, concentrating it into spikes - because the only time that a monostatic radar will see those spikes is when it is illuminating the edge at close to 90 degrees. Note that the longer the edge, the narrower the beam - so a B-2 with its 100-foot leading edges is better off than an F-22, with a spike from its 2-3 foot inlet lip.

Clearly, too, you want those spikes to be angled away from the direction of movement, so that for a given speed the "dwell" of the spike on the radar is as short as possible.

If you know where the radars are, too, and can detect them, you have the opportunity to make a quick weave maneuver as you pass through the critical aspect angle - that is, as the radar is on the same bearing as the spike - to swing the spike quickly across the radar.

Concentrating the signature like this also makes it much easier to use active cancellation, because you only need to make it work for a few seconds.

The most interesting piece of "spike management" in my book is the AGM-129, shaped like a short, fat pencil. The result is a big spike at 90 degrees to centerline, but it does not matter: the threat radar is look-down Doppler, and if your target is travelling at 90 degrees to the radar beam, the Doppler's the same as the ground and you don't see jack.

 

[AeroFranz]

It seems to be from time to time a job I have on this forum is to point out to prolific posters of craziness like Voidmage the wrongness of what they write.

Well, if it makes you feel a little bit better, it wasn't a total waste of time. I consider my self knowledgeable on LO rules of thumb but there at least one more subtle tidbit that I picked up reading this thread, so many thanks to you and those who have the patience to explain.

 

[Spring]

Spring, this is in good tone, you really should read some basics on stealth.

You can use the tone that you want, i have read about stealth, many "facts" are not so, many features are confused as something which help to reduce the RCS, which are not

For example, from the B-2 to the X-47 profile, how many aligned shapes you can count for the front, not many, the x-47 has higher leading edge angle to improve it RCS, the original X-47, was a hopeless diamond, how many "alignements " does it have...(?!)

Of couse, if aerodynamic factors demand a change of it leading edge to other value, then better to check a previous angle and try to make it "aligned"

Aligning things does not reduce the frontal RCS per se, but helps to control it better, to have determined areas where you know your RCS is not good, but what does really matter is the angle of incidence, which should be more than 60º when facing a source, but due areodynamic reasons, and requirements for a fighter it was kept to 40-45º

The original AFT proposal, can be considered stealthy, because it had more angled leading edges, not because it had many surfaces on the same orientation

because the only time that a monostatic radar will see those spikes is when it is illuminating the edge at close to 90 degrees

This is very wrong, first, radar is a wave, second, there are many tricks for some radars to make a return comming from even angled surfaces

 

[bipa]

Sure LowObservable's post brings the level of this thread much higher, but honestly I also understand some of voidimage's views on the topic.

When you consider something is a decisive secret weapon (as stealth aircraft were at some point in the 80's and 90's), you don't want to expose it too much to enemy eyes. Stealth technology has weaknesses and circumstances where it becomes less effective, some of which are difficult to hide, especially when the enemy gets frequent opportunities to test its sensors at your vehicles. In this respect, over-specifying RCS requirements for widely and frequently exposed vehicles ("trivializing" the most advanced technology) might definitely have been considered counter-productive at some point, or even harmful.

Unlikely, though, that such considerations explicitly weighed heavy in the decision to cancel NATF... I guess it may have been a more general problem of specs incompatibility between ATF and NATF, which made the program irrelevant in several respects (RCS probably being a lesser concern).

Just a side comment about Overscan's quick F-22 alignment drawing : only 3D alignment makes real sense, so the edges of the tail fins shouldn't have the same color as the wing's (though their RCS spike angles will indeed coincide in the horizontal plane).

 

[donnage99]

I'm not talking about radars by frequency class, to be exactly

You don't need low frequency to detect one stealthy aircraft at 200km

I find it rather amusing that you call the stealth of the f-22 a myth, even though it's been stated and restated that it's the stealthiest aircraft in the US inventory up to date and proven the effectiveness of its stealth in exercise with the words of many pilots (not just US); you wave off a stealth technique that has become an industry standard in the stealth community, while you gladly accept some magic "radar" can detect stealth aircraft at 200km with no record to prove that up.

I'm more than sure the russians at least have a estimative of the F-22 radar signature, with all these patrols of Bears..but they will want to "study" it for it IFF system and anyway any RCS vaue is important from a mig-21 to a C-5....

Did you read Voidmage's post carefully? It's said that Bears' encounter with f-22 is only once. And the f-22 was carry fuel tanks, hard points, air traffic devices with it that distort its stealth. As for Russians to estimate f-22's RCS, they don't need to send the Bears up there to do that, looking up the internet is much more sufficient.

not because they are afraid of if LO...after all they got a fine example in 1999

I have proven this wrong in the other thread, in which you have yet to be able to counter it, and here you are saying the same thing again.

On the last note, Spring, I think it's important that we don't have the mindset that anything that doesn't fit within the boundary of our understanding is wrong. Stealth technology is a very complex matter, and our understanding of it is at best, "elementary" (no insult intended, as I do consider mine also to be "elementary"). Just because a first grader can only understand to the point and think that the lowest possible number is 0, doesn't mean negative number don't exist. It exist, but it's outside of the kid's boundary.

 

[mz]

Spring, this is in good tone, you really should read some basics on stealth.

You can use the tone that you want, i have read about stealth, many "facts" are not so, many features are confused as something which help to reduce the RCS, which are not

For example, from the B-2 to the X-47 profile, how many aligned shapes you can count for the front, not many, the x-47 has higher leading edge angle to improve it RCS, the original X-47, was a hopeless diamond, how many "alignements " does it have...(?!)

Of couse, if aerodynamic factors demand a change of it leading edge to other value, then better to check a previous angle and try to make it "aligned"

Aligning things does not reduce the frontal RCS per se, but helps to control it better, to have determined areas where you know your RCS is not good, but what does really matter is the angle of incidence, which should be more than 60º when facing a source, but due areodynamic reasons, and requirements for a fighter it was kept to 40-45º

The original AFT proposal, can be considered stealthy, because it had more angled leading edges, not because it had many surfaces on the same orientation

because the only time that a monostatic radar will see those spikes is when it is illuminating the edge at close to 90 degrees

This is very wrong, first, radar is a wave, second, there are many tricks for some radars to make a return comming from even angled surfaces

The "hopeless diamond" has actually the maximum possible amount of edge alignment! Left trailing edge is at the same angle as right leading edge.

One way to look at stealth is to look shapes that are as unstealthy as possible - marine buoy radar reflectors:
Here's the shape, a corner reflector:
http://www.duckworksmagazine.com/07/howto/radar/holdsrain-s.jpg
and here's how well it reflects radar in all directions
http://www.novamarine.ca/RadarReflector2.html

If you shoot a "ray" towards that, it bounces from three surfaces and comes right back at you.

I tried to search RCS polars for some other shapes on the net but somehow can't find stuff like that anymore. I remember seeing them for some stealthy aircraft and they had very low amounts of radar return to the front but at some side angles they had huge but very narrow spikes. I understand this is what edge alignment does - it narrows down the peaks, although the spikes are much taller, it doesn't matter that much if they are very narrow.

 

[voidmage]

Spring, this is in good tone, you really should read some basics on stealth.

Mz,when you suggest to another to “read something on stealth” why you don't point which and where?
At example, Eugene Knott "Radar Crossing Section Measurement" 2006 pag.237-332( for this specific question with Spring) or also, S. Mihailov " Radar cross-section computations and arbitrarily modulated radar waves" (2006)all chapter 4 and pag 416-452- i hope you can find it also traducted in english- (for interaction between singular millimetric complex radar composite wave and various"stealth" shapes),maybe you will discover who in this thread Spring’s words are really the more equilibribated,”bright”,dense of very good intuitions and ,above all,compatible with physics reality! (this is not a polemic,i consider myself a amateur on this specific field- my specialization is in another -,but have however readed ,at now, seven “capital” books on this argument and i think i can who calmly assert who, if in this thread,me comprised, exist a member who don’t need to read something for correct the position it have posted, it is just Spring!).

It seems to be from time to time a job I have on this forum is to point out to prolific posters of craziness like Voidmage the wrongness of what they write

This is the first time in my life i am considered a “believer” or “irrational” ,generally i am always accused of the exact opposite! (little note: i invite all to abandon the dangerous Pig’s metaphor.....in fact,would be even too simple point how the maximum of humiliation would be not losing a wrestle fight with a pig ...but a challenge of intellect).
Overscan can you point to me in the last 30 years another USA air superiority or multirole fighter never selled(in this case for law prohibition!... Amends: H.R.2266 voted at hunanimity!) to any foreign nation ,old NATO allies included,and the precise contingential, strategic and technical motivations for that? Before respond, i invite you to carefully reread my interventions,because from the rational,documented content of your response it must appear absolutely clear not only the fallacy,flimsiness and incompatibility of my position but also the absolute compatibility with the situation diametrically opposite of JSF-F-35 ,you are the administrator and i confide genuinely in your intellectual honesty.

 

[bipa]

I tried to search RCS polars for some other shapes on the net but somehow can't find stuff like that anymore.

You can find some shapes here:

http://lucernhammer.tripointindustries.com/examples/serenity/missile/missile.html

 

[mz]

Voidimage, are you saying that edge alignment is not useful? I don't think you're saying that.

Or do you say that shaping would break the laws of energy conservation or that the ideas of
1) Try to reflect away from the source (V nose, flat bottom, triangular top shape at least) and
2) When you absolutely have to reflect towards the source, do it only at very specific narrow angles (edge alignment helps narrow the angles, since all edges now reflect at the same airplane attitude towards the source, so most of the time no edge at all reflects, if the angles were all over the place, then there might be ten different spikes so a higher probability of detection at any attitude would exist (although each spike would be lower) )

These are some of the basics of stealth in my mind.
I don't remember where I've gotten them from, but they make perfect sense to my physics knowledge and are kinda no-brainers.
If one wants absolutely some source, wikipedia has something
http://en.wikipedia.org/wiki/Stealth_technology

 

[overscan (PaulMM)]

I own Knott's book, and I am somewhat mystified by the conclusions drawn from it.

Here is a figure from the book showing two models, a conventional aircraft and one shaped for low radar cross section. This clearly illustrates how aligning edges reduces the radar signature to small spikes.

The F-22 uses a variety of RCS reduction techniques, but aligning edges remains an important factor.

 

[voidmage]

Overscan if you have readed it,you can easly realize how F-22 airframe's shape(just like sustained by Spring)is a compromise(probably the better achievable) between RCS reduction (the F-117 one and ,also more,the B-2 one are, considering HFS High Frequency Scattering [....for Resonant Scattering and Low frequency scattering is all more difficult ,depending on surface size,dissociated conductivity of the body and incoming wave composition ] ,by far,more efficients,like is easly demonstrable using an advanced TSM- Triangular Surface Meshing- program and foundamental formulas of PTD-Physical Theory of diffraction of Ufimtsef -) and kinematical performances, absurdly high for a VLO platform.
Is for this reason who F-22 is a true miracle and is so jealously protected, in fact design a lower RCS fighter-size aircraft is not so difficult (russian,probably could produce one also in a pair of years),but produce one in the F-22 dBSM level and with its aerodynamics proprieties is a true “brainteaser”,and, at now ,only USA’s scientists have managed to engineerize and realize a similar advanced project....naturally ,in this optic(the only supported by empyrical evidence), JSF project assume a total different countenance.
I am,like all passionate of the field a great “esteemer” of F-22 , but this don’t forbid me to point honestly out who some “figures” of its relative RCS(above all the head on aspect one) are absolutely (physically) out of line when not really laughables( in December 2008 Larry Lawson, executive vice president and general manager of the F-22 program, hoping to win support for F-22 production beyond 183 aircraft,have stated ,with great enphasis-and probably also with an understandable exaggeration-,who from a narrow angle and in certain favourable conditions,F-22’s RCS is almost near to -40 dBSM...) like also some reports of its exchange ratio or the metropolitan’s legends on its engagements(like the F-15 pilot who cannot "lock" its missiles on it despite it can see it with its bare eyes out of the cockpit ...ah ah, i want really to know the neanderthal who have invented this story),then Spring's statements on media heavy reality's distortion ,are surely founded.
Naturally this don’t change who ,at now, F-22 is by far the best fighter at world and this is true until to the point who, for USA, protect its design and technology become a priority more important than assure stability in some “hot” possible war’s theatres(the “compromission” of its technology is probably perceived by american strategists more destabilizing than the lack of a deterrent element)and ,another time ,the difference with JSF’s program setting out become stratospheric...we must simply do a motivation for that ,a motivation who take in account the undeniables physics and technical data and theirs ,equallly undeniable, impact on the strategic choices maked.
Best regards.

 

[voidmage]

Voidimage, are you saying that edge alignment is not useful? I don't think you're saying that.

MZ this type of PO -Physical Optics-scattering regimes calculation have sense only for very High Frequency Scattering and perfectly conducting targets(ideal assumptions)and,like you know, its accuracy is inversely proportional to "gradient" of edges or linear parasitics of the body examined (PO theory includes erroneous contribution due to abrupt discontinuities of current at the shadow boundaries of the surface). PO approximation is also expected to be much more inaccurate in the regions where the GO-Geometrical Optics- current does not produce the dominant scattering
(like in the example you used).
Physical Theory of Diffraction must be used,in this cases, to overcome this discrepancy; in fact, PTD is the superposition of the PO field (originating from the smooth surface) and the field of the equivalent currents on the edge(edge-diffracted field).
I can assure you who also for a high “micro triangle meshe” processing program, the difference between the images you have in your mind of “edge alignment” impact on the resultant diffraction and reality (also in the “ideal” conditions i have pointed before and without the incidence of other contributing factors)are irreconcilables (it ,of course, have a impact, but much, much less pronounced than that resultant from simple GO calculations...it is all much more complex and for this.... also much more interesting. Best regard

Note.: When you can ,try to dodge Wikipedia; if you want to post a elementary reference source (for “starter” consultation),search also a very simple one but at least reliable, i have gived one link some posts ago www.microwaves101.com/encyclopedia/absorbingradar2.cfm#phenomenology

 

[mz]

Thanks for the good reference. Yeah, my examples were related to short waves and large shapes where basically optical phenomena are important - that's just an approximation.

I'm coming to this more from general physics understanding, not much any exact deep understanding of the complex electromagnetic phenomena happening in real life.

It seems (ok, this is a really broad assumption and I'm showing my ignorance here) that if the radar dish is small compared to the total aircraft size (assuming similar spotter and spotted aircraft), so must the wavelength be short compared to aircraft size and thus the electromagnetic phenomena should tend toward similarity with the optical side.
I didn't find a good picture for now, I did find one yesterday.
http://www.radartutorial.eu/18.explanations/pic/streuung.big.gif

 

[bipa]

Voidimage: PO+PTD analysis will indeed accurately estimate sidelobe phenomena from faces/edges, but in my understanding this does in no way contradict shaping rules.

Only at very low frequency shaping becomes inefficient, but the PO+PTD approach is not valid any more when this happens.
Shaping and edge alignment are definitely useful. Because of the low frequency breakdown, one should also try to make fewer, longer edges.
B-2 (and other Northrop LO designs) is a good illustration of those practices.

 

[voidmage]

Shaping and edge alignment are definitely useful. Because of the low frequency breakdown, one should also try to make fewer, longer edges.
B-2 (and other Northrop LO designs) is a good illustration of those practices.

I quote totally your position and ,also more, the example you have chosed (B-2 Spirit: at now,the best realization "shape-wise" of a VLO-optimized aircraft).
Your statement is absolutely correct,nothing can erase general utility of "edge alignement",and this is not my point.
I have only pointed out who,simplifyng a bit that up exposed,its impact in the physical applications is no so unambiguous like a PO modelling of the phenomenon could suggest, in fact it, being a constant parameter subject,conversely,to litterally hundreds of entropycal variables described by not linear or normal -Gaussian- functions, give an operative resource much more relative than that (mistakenly) projected in the common imaginary (and also much difficulf, if not impossible,to predict in planning phase).

Note.: The problem are not only in the low frequency....rather may be, just in these bands ,(like you have already pointed out) the problem become even less crucial -above all for fighter-size aircraft-(in fact ,in these situations,you can ,at maximum,"limit the damages"). Best regards.

 

[sublight]

Ok, which of ya'll is being naughty???

http://tech.yahoo.com/news/nm/20090421/wr_nm/us_pentagon_cyberspying

 

[KJ_Lesnick]

I wouldn't be surprised if the Chinese did it.

 

[Abraham Gubler]

I wouldn't be surprised if the Chinese did it.

I wouldn't be surprised if no one did it... Besides for a project as big as F-35 there are huge amounts of electronic information. Classified information is very different to Top Secret information and the kind of thing that would enable a hostile party to have some kind of combat advantage or head start in replication.

Citing current and former US government officials, The Wall Street Journal claimed classified information about the stealth fighter's design and electronics had been accessed by suspected Chinese hackers.

According to the newspaper, the spies hacked into the company's computer system removing "terabytes of data related to design and electronics systems".

A spokesman for Lockheed Martin's head office in Fort Worth, said: "The article in The Wall Street Journal was incorrect in its representation of successful cyber attacks on the F-35 program. To our knowledge, there has never been any classified information breach.

"Like the US Government, we have attacks on our systems continually and have stringent measures in place to detect and stop atacks."

 

[voidmage]

I think Abraham Gubler's position has definitely a point in this event. The probability who "top end"-sensible technical information has been stealed are very(to the no existence) scarces,this type of risk in a multinational "joint” development program are already taked in consideration from the beginning and, in a certain sense, “programmed” in its possible impact on the project. The damage has been significative ,but very far from disastrous.
Others occasion for different type of technical “theft”,will raise when the diverse components of the aircraft will be mounted,in dozen of locations, by companies of “Level 2 and 3” partner nations ,but likely, also in this circumstances, some securing measures will be taked to reduce the potential damage of a leak to the minimum.
Naturally this is “another cent” on the grounding and the wisdom of the different USA strategic line and choices taked with F-22 program, the greater capacity of a good planner is to foresee and anticipate the problems...... american analysts have demonstred to be very good planners.
Paraphrasing a my old post i can say: “ I know that,you know that,we all know that.....but,above all,long before USA have knowed that”

 

[r16]

while ı know nothing about radars or how they work , ı have this book that says it has always been the convention to measure RCS in square meters . But ı have seen it in this thread the claimed f-22 number is something like -40 db or whatever . What is this in squaremeters ? And the inevitable question

a)Are the numbers for true Stealth aircraft so small that they make the convention cumbersome to use ? Realistically this has to be the one

b) that the value for a B-17 was 170sqm makes it possible for a conspiracy theorist to claim the present day Americana sees it improper that the lead in VLO might somehow be shaken by the impression that the measuring convention "was not invented here" ?

 

[TomS]

RCS is frequently measured in decibels relative to a square meter (dBsm). To convert a figure in dBsm to square meters, the formula is:

m2 = 10(dBsm/10)

So -40dbsm = 10(-40/10) = 10-4 = 0.0001m2

 

[voidmage]

R16 i have searched for you this link ,in it is explained with simplicity the motivations for dBSM utilization : radarproblems.com/chapters/ch06.dir/ch06pr.dir/c06p11.dir/c06p11.htm

I can add also who a logarithmic unit of measurement aid to more effectively express the correlated power physical quantity, specially for no linear functions describing the phenomenon (like a radar's tracking range related to RCS variation).

Best regards.

 

[donnage99]

in December 2008 Larry Lawson, executive vice president and general manager of the F-22 program, hoping to win support for F-22 production beyond 183 aircraft,have stated ,with great enphasis-and probably also with an understandable exaggeration-,who from a narrow angle and in certain favourable conditions,F-22’s RCS is almost near to -40 dBSM...

Make me remember what Bill Sweetman wrote:"How low can LO go? One paper, co-authored by a principal in DenMar Inc., the company founded by Stealth pioneer Denys Overholser, refers to the development of fasteners for a body with an RCS of -70 dB./sq. meter -- one-thousandth of the -40 dB. associated with the JSF, and one-tenth that of a mosquito. DTI queried RCS engineers who don't believe such numbers are possible; but then, when mention of a -30 dB. signature leaked out in a 1981 Northrop paper, nobody believed that either."

like also some reports of its exchange ratio or the metropolitan’s legends on its engagements(like the F-15 pilot who cannot "lock" its missiles on it despite it can see it with its bare eyes out of the cockpit ...ah ah, i want really to know the neanderthal who have invented this story),then Spring's statements on media heavy reality's distortion ,are surely founded.

The f-15 pilot was Australian pilot Stephen Chappell. Here's the original quotation from USAF website:
"'I can't see the [expletive deleted] thing,' said RAAF Squadron Leader Stephen Chappell, exchange F-15 pilot in the 65th Aggressor Squadron. 'It won't let me put a weapons system on it, even when I can see it visually through the canopy. [Flying against the F-22] annoys the hell out of me.'"

There's another incident as far as I know concerning the raptor's stealth in WVR is when the raptor slips behind an f-16 and score a gun kill without being noticed.

 

[voidmage]

Donnage99 i seriously think who for your point you have definitely cited the wrong person. If we talk of the most authorative expert who respond to the name of Bill Sweetman (Editor in Chief of Defense Technology International, co-director of Aviation Week Group and first referent for Advanced Aeronautics Technology for Jane’s Defence) i must sadly inform you who it (like the majority of experts and scientists at world)is,using a word much common in this forum, a blind “believer”, read this articule:
www.aviationweek.com/aw/blogs/defense/index.jsp?plckController=Blog&plckScript=blogScript&plckElementId=blogDest&plckBlogPage=BlogViewPost&plckPostId=Blog%3A27ec4a53-dcc8-42d0-bd3a-01329aef79a7Post%3Ab1c3536a-8d96-481f-aef5-d6428ec6f9ca
this could be placed in a APA NOTAM also instantly or below the name of Carlo Kopp and nobody could doubt of the attribution).
I simply refuse to believe who it have stated a similar no sense ("-40 dB, associated with the JSF" ),unless it refere to the association maked by the platitudes of the common opinion.

For the -70 dB question ,naturally, at a purely accademic level,taking in consideration only the “now in use” RCS reduction technologies, reaching this would be even virtually possible, on a perfect 7 degrees“head on” aspect angle(but erase from your mind a fighter with this relative dBSM.... a similar aircraft would be a B-2-like,but aerodynamics-wise largely more “clumsy” than it).
The problem,like you well know,is who in the function describing radar’s acquisition's range in relation to target object's RCS, placing in the x axis the dBSM of the target and in Y the range at wich the locking-on occur,the function’s curve tend,from the -20 dBSM mark, asymptotically to the x axis; this naturally implie who the impact on the degradation of radar’s tracking range of values of RCS lower than - 30 / - 40 dBSM,become exponentially less influenzial,but conversely its impact on reasearch and realization’s costs (beside the ever groving “erosion” of aerodynamics performances)become exponentially highters.
I give you a example of that : a APG-79 AESA radar’s (F/A 18 E/F) tracking range pass from 156,7 to 86,4 NMI [Nautical Miles] for a change of target RCS dBSM from +10 to 0( 10 to 0 square meters) or about -70 NMI of range’s degradation,from 46,8 to 29,1 NMI for the -10 -20 dBSM segment (0,1 to 0,01 square meters) or about 18 NMI of degradation and from 17,2 to 13,8 NMI from -30 to -40 (0,001 to 0,0001 square meters) or about few more than 3 NMI of degradation.....from -60 to -70 dBSM it will become a difference of about 160 meters!!!a who,conversely, force you to spend dozen of billion dollars in research and transform your aircraft in a.... flyng hippopotamus... it is hardly stimable like a evolution.

"'I can't see the [expletive deleted] thing,' said RAAF Squadron Leader Stephen Chappell, exchange F-15 pilot in the 65th Aggressor Squadron. 'It won't let me put a weapons system on it, even when I can see it visually through the canopy. [Flying against the F-22] annoys the hell out of me."

I sincerely hope who you have posted this statements for laugh of it with me and the others....a AGAT 9B -1348 (the seeker of the base R-77 missile)has a function describing its acquisition range of LO or VLO targets pratically “flat”( asymptotic) from -20 dBSM onwards(it remain in the difference comprised in less than half a NMI!!) ,in fact, without even considering a IR seeker ...by far the most commons WVR, the less is the starting power aperture of the radar the less pronunced is the curve in a similar function. If the story is true (but i don’t think so, probably this pilot is only a unaware victim of the notorious “metropolitan legend’s virus” ) that is the greater idiocy ever uttered by a man on the argument...and,indeed, a true stain of dishonour on this pilot’s uniform

 

[overscan (PaulMM)]

Voidmage, you are banned for a week.

Insulting posts about a well known author and stealth expert (and regular visitor to the forum) and a serving pilot who's flown against the F-22 had better be backed up with serious technical knowledge, I see no evidence you know what you are talking about. Quoting from interesting articles or books doesn't make your points any more valid.

I suggest you learn to post respectfully or find another forum to frequent.

 

[donnage99]

Donnage99 i seriously think who for your point you have definitely cited the wrong person.

He was referring to the official data released from the air force.
http://aviationweek.com/aw/generic/story_generic.jsp?channel=dti&id=news/DTI-Bomber.xml
This is the mindset of a typical authoritative expert. He remains skeptical, but doesn't outright oppose it, because he knows that he is but an outsider in the end, and though something might not fit into the boundary of his understanding on the subject, that doesn't mean it's BS. So though he doesn't happily embrace it, but he still accept it. This also applies to the article you quoted. He doesn't oppose the given stealth numbers of the f-35. He is simply stating that APA puts a hell of more effort in their argument than Lockheed.

 

[rousseau]

Will the US Air Force buy the Boeing F-15 Silent Eagle in the interim? Or will the F-15 Silent Eagle be an export only aircraft?

This depends on a very important point which is how stealth the F-15SE really will be? For the question, the precondition also is what aspects does stealth rely on more: profile or paint?
A further step, doubtless, stealth is a revolutional capability for air-combat, but does that mean traditional capability is going to be unimportant?
Back to quote is what position the F-15SE is in those two questions above?

I've read 5 pages of this thread, but a thread like this anywhere always be digression. So I lost my patience almost.

 

[donnage99]

I don't see the Air Force buying more f-15SE. I don't see the reasoning in stopping the f-22 production and go buy the f-15SE. What I'm guessing is that the Air Force will upgrade its current f-15E to f-15SE as Boeing has said that it's possible to do so.

 

[KJ_Lesnick]

I believe the source. But I'm wondering why couldn't he put a heat-seaker on the F-22... Is it's thermal signature that good?

Consider me impressed


KJ Lesnick

 

[Abraham Gubler]

In fighters without a helmet mounted curing system (JHMCS) the AIM-9 seeker is cued onto the target by a radar track.

 

[r16]

thanks for the replies regarding decibels